This R&D program is to 1) design and assemble a high energy (kVp) photoelectronic digital mammography system, using a screen-CCD based digital system, and 2) demonstrating its advantages relative to "state of the art" film-screen mammographic systems. Phase I is directed to a detailed study for early detection of breast cancer using much higher energy x-ray photons than is customary. With a Gd202S screen e.g., preliminary analysis indicates superior diagnosis can be carried out with photons above the k edge of gadolinium (50.23 keV). In general, the R&D is concerned with imaging of calcifications and soft tissue tumors using a tungsten tube operating in the range of 50-150 kVp, and demonstrating that preliminary theoretical analysis predicting improved diagnosis is valid for resolving low contrast objects. Research to date indicates that this new direction for mammography offers the opportunity to increase the sensitivity of the test and substantially reduce the number of false positives.